FREENAS NOOB!! Quick Question (or two)

[derekholland]

I installed Freenas 8.01. This is cool stuff and I am loving it. Anyway, I have 4 x 2 TB drives and a Gigabit network. I am using this NAS for a VMWAre lab. Since I have so much storage, I want to also use it for backups and simple storage, like movies and MP3s. I notice that when I copy large files, 4-8 Gig, it takes a long time and the network is barely getting hit. Maybe 10 Meg at most. Running Perfmon, it appears that my bottleneck is the disks. I setup my disks as Raid 5 on a Highpoint Raid controller card and a ZFS volume. I am going to remove the raid from controller, setup JBOS, and then create the RAID within FREENAS. I was wondering if adding a SSD drive would help with performance? If it can help, how would it best be setup?

I don't have the SSD yet. I was going to get a Crucial C300 64 Gig. I am open to other options. Thanks in advance to any and all help.

 

[kashiwagi]

You should be able to saturate a gigabit port without using an SSD. Just make sure you expose the disks directly for use with ZFS, and then you can work from there.

Also, your setup will depend on what your requirements are for speed vs. redundancy. You could do one vdev with 4 disks in RAIDZ1, or maybe a mirrored stripe for more performance.

Try some different setups and benchmark along the way, and I am pretty sure you won't be needing to spend money on an SSD.

What type of activity are you expecting? (e.g. lots of small random writes, or maybe long sequential reads?). I love ZFS for my needs, but it is not _always_ the best choice.

 

[derekholland]

I will look at the RaidZ1. I was thinking that sending large files to an SSD or Raptor drive could be accomplished and then the system can move the data to the RAID5 storage later, since it is slower disks. I just don't know if that is possible and if so, what is that feature called?

Thanks for replying.

 

[kashiwagi]

You can use a feature called ZIL (ZFS intent log, I think), as kind of a write cache. This can give you a nice boost in write performance (especially many small random writes, like heavy NFS usage).

The thing with a ZIL SSD drive is that if it gets corrupt, your entire zpool is toast. That has been fixed in ZFS version 19 and upwards, but FreeNAS is only at version 15 currently (I think). So you would have to have redundancy for your ZIL drive (e.g. a mirrored SSD).

To summarize, what you are thinking about exists, and can be done (just google "zfs zil"), but beware of the pitfalls. http://forums.freebsd.org/showthread.php?t=18221

If you want a read cache, that is called a zlog. http://www.nerdblog.com/2010/03/zfs-nas-followup-ssd-is-amazing.html

 

[ProtoSD]

Kashiwagi is absolutely correct. There have been at least a couple of people here on the forums that wanted to try the same thing and in one accident or another messed up their ZIL disk and lost their data. There are a lot of other things to look into to tune your performance before you need to use ZIL, it's not worth the risk. Wait for a newer version of ZFS and then consider it.

The thing with a ZIL SSD drive is that if it gets corrupt, your entire zpool is toast. That has been fixed in ZFS version 19 and upwards, but FreeNAS is only at version 15 currently (I think). So you would have to have redundancy for your ZIL drive (e.g. a mirrored SSD).

To summarize, what you are thinking about exists, and can be done (just google "zfs zil"), but beware of the pitfalls. http://forums.freebsd.org/showthread.php?t=18221

 

[derekholland]

Thanks, I appreciate the help and suggestions.

 

[derekholland]

I created a Raid1/0 using 4 x 2 TB Hitachi drives. I am using a Highpoint Rocket Raid Controller 2300 with 4 connectors. When I got into Freenas, made my Raid drive ZFS and added the Cache drive (WD Raptor). My Freenas unit has 4 Gig ram. I am doing a backup of 2 TB to this NAS and I am averaging 17 Meg a sec. I linked 2 Gig ports off the Freenas device and the backup server has 1 Gig with a Cisco Gig switch. Seems to be unbelievably slow to me. Any thoughts?? Copying large files is also very slow.

 

[ProtoSD]

Hi Derek,

Question #18 in the FAQ has a few things to try, have you had a look there? Follow the 'Unoffical FAQ' link in my signature below.

 

[derekholland]

I have it now where if I FTP to my Freenas, I can get approximately 300 Meg/Sec. If I connect to Freenas unit hosting NFS (running Windows 2008 server with NFS Services - client), I can copy files and get 80 Meg/Sec. Therefore it is a little better. Especially, using FTP. Why is CIFS so slow? I am using iScsi for VMWare which seems to be about the same speed as NFS.

 

[derekholland]

Also, I ran Iperf. I can average 750-800 Meg/Sec. I am using a Cisco SG300 Gigabit switch. All my NICs are gig and the switch reports this.